1994 Lumina APV Headaches!

[TaiN]

Hello all I have lurked around for an answer for my problem and did not get it. 1994 lumina APV with 3.8 and about 178k miles. A few weeks ago I was driving 70 mph and noticed my speedo was cutting out but not all the way. After turnning off radio , blower ect... it lost all power and then came back to life. 2 miles down the road it dies. without pulling off the road I shifted into netural and restarted and drove it home without any problems execpt I noticed my volt meter was at a low 10 volts. Going to the auto parts store to get it tested they said my alternator was only putting out 50 amps. Replaced the alternator (btw my battery is just over a year old) That worked for about 2 weeks and now again my volt meter is down to below 10 volts. On my way to work today ever time I put on my blinker or anything else that takes power it affects my speedo and the van barly has enough power for spark. What could be taking that much volatge without blowing a fuse???? ECM perhaps? Bad battery? should I put stock plugs back in? I have Bosh plat's in now Thanks in advance for any help anyone can provide. I will be sure to follow up with the fix that worked.

[TaiN]

Oh and btw I have never got any codes or check lights ever

[BluBowTie]

Check the battery connections/cables. On the inside of the side terminal cables, make sure they aren't green, or corroded. Also check the ground. Just because the battery is new, doesn't mean its a good one. Have it load tested.

You may be able to duplicate the problem by running the engine, then open the hood and wiggle the battery connections. Do this with as many electric options on such as lights on bright, heater fan on high, defrost, etc.

[TaiN]

First thanks for the reply. I followed all ground wires to where they terminate. Nothing looked corroded but I cleaned them anyways. After all that I started it up and checked with volt meter while running...with nothing extra on and got a reading of 10.28 volts. Just to see what would happen I turned everything on and finally got a check engine light. The volt meter started dropping like crazy until I hit 4 volts. Yes for some reason the engine keep running.


-Edit

oops I left something out, When I started it to see if I could get it to stall out, I had it in drive with me on the brake

[TaiN]

ok I took the van to this guy who rebuilds alternators and he said that it was my computer going out. He told me that without the van started but the key in the "on" position unplug the harness clip on the alternator and meter out the middle pin to see if you get 12v if not my computer is bad. Any truth to this??

[jeffcoslacker]

Sounds to me like you just got a bad rebuilt alternator. I put hundreds of them on GM 3.8's, about 2 in ten came back defective 'till we went to AC Delco reman units. The extra cost is worth it. And if you bought that one from AZ or Advance, I'd almost guarantee that's the problem. See what you voltage reads at the large post on the back of the alternator with the motor running.

[TaiN]

I thought that to! But I'm starting to think that it's not. Before I left to get it tested at AZ. I took a meter reading and it was at 10.23volts. Ironicly as I was pulling into the parking lot it dies. It did not even make a clicking sound when I tried to restart. After a few of them help me get the van out of the way of others. They took thier little booster pack and jumped me and all of a sudden now i'm getting 13.50 volts with all Accories on. They and the alternator guy ( at the other place ) both said that It sounded like after the battery was drained and got jumped that it reset the computer and it would pick it's time to start the whole cycle again. I don't dispute that it might be the alternator but both the old one and the one I just bought are doing the exact same thing. I had 3 different places test my old one and they all said that it was still good.

[TaiN]

I always thought the computer was called the ECM. In the service manual is it called the PCM?

[richtazz]

The pcm is a newer version of an ECM. Instead of using a e-prom, the PCM is flash programmable, and learns on the go. I would bet your problem is either a dead cell in the battery, or a broken wire that turns your alternator on and off. I'm not sure which wire it is on your APV, but the wiring diagrams in the back of a HAynes manual will tell you. There is one wire at the voltage regulator plug on the alternator that has power all the time, and another that only has power with the ignition on, that's the wire you're looking for. On most cars, it's white, but not all. This wire "energizes" the regulator, and turns the alternator on. But with only 10v, I think your new battery may have a dead cell. Each cell produces 2.2 volts, and if you have a bad cell, the alternator will not turn on. it's a safety feature to keep a bad battery from overheating and killing the alternator.

[TaiN]

Well I replaced the computer today and all of a sudden all my volts are back. I get a reading from the battery of 13.40 but I get a reading of 14.50 at the alternator. Is this normal or do I still have a battery problem? I checked out all the wires and nothing looks to be broken. Do I have to goto a dealer to get my chip flashed or is that even a good idea? The new computer required me to put my old chip into the new unit. The computer was only 100.00 so that was no big deal. Before I was also getting that TCC shutter between 3-4 gear and that has seemed to go away at this point but I haven't driven it far enough yet to tell.

[richtazz]

everything is now peachy keen. the battery should read 13 to 13.5 fully charged, and the alternator should read a little higher, to allow recharging of the battery as well as running the accessories.

[TaiN]

ok i'll start to drive it now on a regular basis, Report back with any problems, thanks for all the replys!

[tigerfreak36]

hey tain did u put the computer in your self? and if u did was it hard to do? and u said it told u to put your old chip back in what chip is that thanks Rick

[TaiN]

yep got it myself. Not really hard,trick I found was take the glove box out and tilt the unit out throu that hole. I could not get the thing to come straight down. The chip was a flash programmable chip. It's the one if you were to buy a performance chip that's were it would go. (Experts may correct me if i'm wrong )

[tigerfreak36]

well great thanks much i have the exact same van u do. A firestone told me it would cost 300 for a new computer and to put it in i thought damn, but i didnt need one one in the future who knows